import { createApp } from 'vue'
import App from './App.vue'
import router from './router'
import store from './store'
//1.引入element-plus组件库
import ElementPlus, {ElMessage} from 'element-plus'
import 'element-plus/dist/index.css'
//3.引入element-plus图标库
import * as ElementPlusIconsVue from '@element-plus/icons-vue'
//5.1修改elementPlus默认中文
import zhCn from 'element-plus/dist/locale/zh-cn.mjs'

//9.1配置根路径
const BASE_URL = 'http://localhost:8081';
//window是浏览器内置的全局对象，给它设置属性就是全局属性，可以在任意的Script标签中使用
window.BASE_URL = BASE_URL;

const app = createApp(App)
//9.2给app(vue实例)也设置根路径，这样可以在任意的template标签中使用！
app.config.globalProperties.BASE_URL = BASE_URL;

//4.遍历ElementPlusIconsVue对象中的所有图标组件并注册到app中
for (const [key, component] of Object.entries(ElementPlusIconsVue)) {
    app.component(key, component)
}

//2.app.use(ElementPlus) 使用Element-plus组件库
//5.2 app.use(ElementPlus,{ locale: zhCn })将El本地化为中文
app.use(ElementPlus,{ locale: zhCn }).use(store).use(router).mount('#app')

//6.解决ResizeObserver Error
const debounce = (fn, delay) => {
    let timer = null;
    return function () {
        let context = this;
        let args = arguments;
        clearTimeout(timer);
        timer = setTimeout(function () {
            fn.apply(context, args);
        }, delay);
    }
}
const _ResizeObserver = window.ResizeObserver;
window.ResizeObserver = class ResizeObserver extends _ResizeObserver {
    constructor(callback) {
        callback = debounce(callback, 16);
        super(callback);
    }
}

//7.配置全局方法,获取当前登录人的数据
window.getUser = () => {
    return localStorage.user ? JSON.parse(localStorage.user) : null;
}

//8.配置路由守卫
//to 即将进入的目标路由对象
//from 当前导航正要离开的路由对象
//next 是一个函数，表示路由是否可以继续进行
router.beforeEach((to, from, next) => {
    let user = localStorage.user;//从localStorage中获取用户数据
    if(to.path!=='/login' && !user)//如果目标路径不是登录页且用户不存在
        //就跳转到登录页,且弹出提示
        next({path: '/login'},ElMessage.error('请先登录!'));
    else
        next()//如果目标路径是登录页,或用户已登录,就直接放行,允许路由跳转
})